1. Field of the Invention
The present invention relates to a method and a system for filling a straw with a liquid.
2. Description of the Prior Art
Straws, widely used to store small quantities of substances, in particular biological substances and especially biological liquids, were described for the first time in French patent No. 995 878. The straws, referred to as "French straws", used to include a three-part stopper made up of two wads of a fibrous substance with a powder between them which was transformed on contact with a liquid into an impermeable paste or gel adhering to the wall of the tube, creating a sealed stopper.
IMV TECHNOLOGIES straws with a three-part stopper are entirely satisfactory. Nevertheless, some absorption of the liquid contained in the straw has been observed, although at a very low level. IMV TECHNOLOGIES have therefore developed a straw with a hydrophobic microporous one-piece stopper also referred to as a "non-absorbent stopper". A straw of this kind is described in IMV TECHNOLOGIES' French patent application FR-A-2 762 210 of Apr. 21, 1997.
Straws with a three-part stopper are filled horizontally by aspiration. The liquid to be packaged is drawn into the horizontal straw using a suction pump. Filling a horizontal three-part stopper straw is described in particular in patent application EP-A-0 480 109 (IMV TECHNOLOGIES).
This system is entirely suitable for small diameter straws but is not suitable for large diameter straws. In the context of the present invention, the expression "large diameter" means a diameter greater than or equal to approximately 3 mm.
An object of the invention is to provide a method of filling large diameter straws with a liquid.
Other objects and advantages of the invention will become apparent on reading the following description.